EFFECT OF THE SIZE FACTOR ON PSYCHOLOGICAL THREAT OF A MOBILE ROBOT MOVING TOWARD HUMAN

Abstract

Although human symbiosis service robots have been developed in various sizes, there have been few quantitative investigations on the psychological effect that the size of a robot has on the user. We focused on the height of a robot (robot size), its relationship to the degree of fear or anxiety experienced by a human interacting with the robot, and the appropriate human-robot distance. We prepared three mobile robots measuring 0.6, 1.2 and 1.8 m tall. In our experiment, one of these robots would approach a male subject from a distance of 3 m at up to 0.4 m/s, and the subject would use a switch to stop the robot when he felt anxious. We measured the human-robot distance at the point when the subject stopped the robot. Then we asked the subject to fill out a questionnaire to evaluate the difference in degree of anxiety for robots of different sizes. Experiments with 19 subjects showed a tendency towards a longer human-robot distance for a larger robot. The questionnaire results revealed that the subjects felt maximum anxiety for the 1.8-m-tall robot although some subjects experienced anxiety in the case of the 0.6-m-tall robot, too. The results for both human-robot distance and the questionnaires will be useful in designing service robots.